Klinefelter Syndrome

What is Klinefelter Syndrome?

Klinefelter syndrome is a chromosome disorder that affects male physical and cognitive development . While the cause of Klinefelter syndrome is genetic, it is not inherited. Humans have 46 paired chromosomes, made up of two sex chromosomes that determine gender and 44 chromosomes that determine other factors. A boy with Klinefelter syndrome has an additional X chromosome. The normal male chromosome arrangement is 46XY, but men with Klinefelter’s syndrome have 47XXY. The extra X chromosome can come from either parent. This is thought to be caused by an error within the fertilised egg or the dividing cells as the baby develops. The presence of the Y chromosome ensures male sexual characteristics but, because the testicles are underdeveloped, there may not be enough testosterone production. Some researchers suspect that advanced parental age may be a risk factor.

What are the Signs of Klinefelter Syndrome?

Signs that may be apparent in childhood include:
  • Delays in starting to talk or walk
  • Learning difficulties, including trouble listening or concentrating in class
  • Poor motor development or coordination
  • Tiredness and fatigue
  • Reduced muscle strength or tone
Signs that may be apparent at puberty include:
  • Tiredness and fatigue
  • Unexplained weight gain, especially on the stomach or trunk
  • Poor muscle development
  • Breast tissue development
  • Small testicles and penis
  • Lack of facial, pubic and underarm hair
  • Disproportionately long arms and legs compared to the length of the body
  • Taller than average height
  • Single crease in the palm (simian crease)
  • Difficulties with sexual functioning
  • Sadness, lowered mood or depression.